• Journal of Biosystems Engineering
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• 제22권1호
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• pp.41-48
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• 1997

A nondestructive quality inspection technique using acoustic impulse response method was studied to investigate the feasibility of egg shell inspection. An experimental system was built to generate impact force, to measure the response signal and to analyze the frequency spectrum. This system includes an impulse generating unit, an egg holding seat, a microphone with preamplifier, and a digital oscilloscope connected to Personal Computer by RS-232C interface. The factors such as impulse generating method, egg holding method, and sensor location were evaluated by analyzing the power spectrum density of the measured signal. The results obtained are summarized as follows : 1. From the sampled eggs, the proper conditions for detecting damaged eggs were found as followings; ceramic for the impact ball material, rubber for egg seat material, 20 degrees for an impact angle of pendulum, 10mm for the distance between egg and sensor, the sharp side for impacting part, and 180 degrees for the location of sensor. 2. Examination of the Fourier transformed analysis in beth normal and damaged eggs revealed that those factors such as the resonant frequency, a number of peak frequencies and the magnitude of power spectrum were important to detect damaged eggs.

• KIEE International Transactions on Power Engineering
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• 제4A권2호
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• pp.73-78
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• 2004

This paper proposes a framework for determining the minimum load shedding for restoring solvability. The framework includes a continuation power flow (CPF) and an optimal power flow (OPF). The CPF parameterizes a specified outage from a set of multiple contingencies causing unsolvable cases, and it traces the path of solutions with respect to the parameter variation. At the nose point of the path, sensitivity analysis is performed in order to achieve the most effective control location for load shedding. Using the control location information, the OPF for locating the minimum load shedding is executed in order to restore power flow solvability. It is highlighted that the framework systematically determines control locations and the proper amount of load shedding. In a numerical simulation, an illustrative example of the proposed framework is shown by applying it to the New England 39 bus system.

• 산업공학
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• 제24권1호
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• pp.15-23
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• 2011

This study considers paging schemes that can page some cells or only one cell within the location area to reduce paging cost by using PAs (Paging Agents) and compares their performances by using a new analytic method. There are three ways of paging schemes using PAs; BSPA (Base Staton Paging Agent), 2SPA (2-Step Paging Agent), LAPA (Location Area Paging Agent). This study proposes exact performance of BSPA and 2SPA using a new analytic method based on Markov chain modeling to find the most efficient paging scheme. Numerical results for various circumstances are presented by using proposed analytic method to select a proper paging scheme in mobile communication networks.

• 한국안전학회지
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• 제24권4호
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• pp.82-89
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• 2009

Unlike concrete bridge, steel bridge resists external force by forming thin plate. Thus, because steel girder bridge has big slenderness ratio, buckling is a major design factor. Plate girder consists of flange and web plate. Because of economic views, web plate that resists shear forces is made by more thinner plate. Thus, web plate has much risk for buckling. The objective of this study is to analyze the buckling behaviors of plate girder and to present the proper reinforcement location of longitudinal stiffeners. Various parametric study according to the change of web height, transverse stiffeners and load condition are examined.

• Clinical Pain
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• 제20권2호
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• pp.59-69
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• 2021

Patients with pain, numbness, and weakness in their elbows, wrists, and hands often need proper rehabilitation treatments. Among them, musculoskeletal injection therapy should be performed after a full evaluation of the patient, taking into account history and physical examination leading to clinical diagnosis. General rules such as accurate diagnosis and injection materials selection are used to achieve maximum benefit with minimal side effects. During injection, patient location, aseptic care, penetration techniques, follow-up and follow-up care must be maintained. Specific techniques may vary depending on the type, lesion, and location of the injection therapy. For optimal effectiveness, physician should inject directly into the lesion and avoid the injection of surroundings as much as possible. Therefore, ultrasound-guided injections are needed to accurately inject. These conditions and other conditions of the hands, wrists, and elbows can be effectively diagnosed and treated with diagnostic ultrasound and ultrasound-guided injections.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.235-236
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• 2022

In the present study, the effect of horizontal vent position on fire phenomena in the enclosure with vertical and horizontal vents was examined using numerical simulation. Case 1 indicates the condition that the horizontal vent is in the center of the ceiling. Case 3 indicates the condition that the horizontal vent is far away from the vertical vent. Case 2 indicates the condition that the horizontal vent is installed between Case 1 and Case 3. The temperature distribution, smoke layer temperature, velocity distribution, and mass flow rate of horizontal vent flow were analyzed. In Case 2, the temperatures were lowest and the mass flow rate through the horizontal vent was largest. This is because the flame is inclined by the inflow through the vertical vent. Hence, to determine the proper horizontal vent location for the high smoke ventilation performance, the inflow through the vertical vent and its effect on flame behavior should be considered.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.17-22
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• 2011

A considerable number of construction disasters occur on pathways. Safety management is usually performed on construction sites to prevent accidents in activity areas. This means that the safety management level of hazards on pathways is relatively minimized. Many researchers have noted that hazard identification is fundamental to safety management. Thus, algorithms for helping safety managers to identify hazardous areas are developed using automated data collection technology. These algorithms primarily search for potential hazardous areas by comparing workers' location logs based on a real-time location system and optimal routes based on BIM. Potential hazardous areas are filtered by identified hazardous areas and activity areas. After that, safety managers are provided with information about potential hazardous areas and can establish proper safety countermeasures. This can help to improve safety on construction sites.

• International Journal of Computer Science & Network Security
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• 제24권8호
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• pp.174-178
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• 2024

IoT is collection of different "things" which are associated with open web. As all the things are connected to the Internet, it offers convenience to end users for accessing the resources from "Any Where, Any Time" throughout the globe. At the same time, open nature of IoT provides a fertile ground to an intruder for launching different security related threats. If we can no apply proper security safeguards to the IoT System, then it will be not useful to society. Authentication, Encryption, Trust Management and Secure Routing are different domains to offer security in IoT system. Among them, Authentication is very much important security service as it validates device identity before granting access to system services/ resources. Existing IoT Authentication algorithms are fail to verify device identity in unambiguous way. They are vulnerable to different security threats such as Key Stolen threat, MITM threat and Location Spoofing threat. So, it is a demand of time to design an efficient and secure Multi-factor IoT algorithm which can offer better security and validate device identity in unambiguous way.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.853-858
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• 2000

The working fluid from the combustor to the turbine stage of a gas turbine makes various boundary layer thickness. Since the inlet boundary layer thickness is one of the important factors that affect the turbine efficiency. It is necessary to investigate secondary flow and loss with various boundary layer thickness conditions. In the present study, the effect of various inlet boundary layer thickness on secondary flow and loss and the proper height of the boundary layer fences for various boundary layer thickness were investigated. Measurements of secondary flow velocity and total pressure loss within and downstream of the passage were taken under 5 boundary layer thickness conditions, 16, 36, 52, 69, 110mm. It was found that total pressure loss and secondary flow areas were increased with increase of thickness but they were maintained almost at the same position. At the fellowing research about the boundary layer fences, 1/6, 1/3, 1/2 of each inlet boundary layer thickness and 12mm were used as the fence heights. As a result, it was observed that the proper height of the fences was generally constant since the passage vortex remained almost at the same position. Therefore once the geometry of a cascade is decided, the location of the Passage vortex and the proper fence height are appeared to be determined at the same time. When the inlet boundary layer thickness is relatively small, the loss caused by the proper fence becomes bigger than endwall loss so that it dominates secondary loss. In these cases the proper fence hight is decided not by the cascade geometry but by the inlet boundary layer thickness as previous investigations.

• 한국인터넷방송통신학회논문지
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• 제13권1호
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• pp.229-234
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• 2013

스마트폰의 보급과 위치 기반 서비스의 활성화로 스마트폰을 기반으로 하는 위치정보 서비스의 필요성과 중요성이 매우 중요해지고 있다. 그러나 기존의 방법들은 경제성이나 편의성, 정확도의 부족으로 실용화가 어려운 상황이며, 무선랜의 신호세기를 이용한 방법은 정확도가 떨어지는 문제가 있다. 본 논문에서는 스마트폰의 음향신호와 블루투스 통신 방식을 이용한 상대위치 인식 기술에 대한 기술적 배경과 구현 기술 및 측정 결과에 대해 기술하였다. 이 기술은 저렴한 구현 비용의 단일 장치로 스마트폰의 정밀한 측위가 가능하며, 특히 실내에서의 위치기반 지능화 서비스에 적합하다.